The present invention concerns a plate heat exchanger for at least two heat exchanging fluids which heat exchanger is permanently joined and comprises at least one core of plates with a plurality of heat exchanging plates and at least two end plates, the heat exchanging plates creating plate interspaces between each other.
EP, A1, 0 551 545 shows an oil cooler without a housing. Heat exchanging plates are on one side covered with a sacrificial corrosion layer 73 and on the other side covered with a solder material 75 for brazing, see for example FIG. 8. The plates are turned in such a way in the core of plates that every other plate interspace, which is aimed for water that is cooling, shows heat exchanging plate areas with a sacrificial corrosion layer only while the rest of the plate interspaces, aimed for the oil to be cooled, shows heat exchanging plate areas with layers of solder material only. In this way the risk of corrosion in the plate interspaces with water is reduced at the same time as these plate interspaces show a minimum amount of solder material. In order to be able to braze the core of plates together however one has been forced to modify the visual appearance of the edges for half the number of plates. Such modifications are expensive.
The purpose of the invention is to create an inexpensive plate heat exchanger for cooling of beverages or the like in which heat exchanger a significant less amount of solder material is present in those plate interspaces where the beverage is to pass than in of the rest of the plate interspaces. The invention thus comprises a plate heat exchanger for at least two heat exchanging fluids which heat exchanger is permanently joined and comprises at least one core of plates with a plurality of heat exchanging plates and at least two end plates. The heat exchanging plates create plate interspaces between each other.
Each one of the heat exchanging plates is provided with one or several corrugations which vertically extends/extend within an area bounded by two at a distance from each other situated parallel first and second planes respectively and which both are mainly in parallel with all the heat exchanging plates as well as with the end plates of the plate heat exchanger. Each one of the heat exchanging plates is provided with at least four port holes being parts of an inlet channel and an outlet channel through the core of plates for each one of the fluids.
At least one of the end plates has a plurality of port holes each one communicating with one of the inlet channels or one of the outlet channels and the inlet channels and the outlet channels for a first and a second fluid respectively are in fluid communication with a first and a second set of plate interspaces respectively.
The heat exchanging plates have outer edges of a similar design. On each other bearing heat exchanging plates in at least each one of the plate interspaces being parts of the said first set of plate interspaces are brazed together in their outer edges, around at least two port holes as well as in preferably all of those points upon the heat exchanging plates where the respective corrugations bear on each other while on each other bearing heat exchanging plates in at least each one of the plate interspaces being parts of the said second set of plate interspaces are brazed together in their outer edges and around at least two port holes only.
The characteristics in other respects of the present invention are clear from the following patent claims.